ST. LOUIS -- It is perhaps a tribute to the vast array of exciting young pitchers on the St. Louis Cardinals that Joe Kelly, a 25-year-old who just completed his season with a 135 ERA+, is largely an afterthought when Cardinals pitching is discussed.

Earlier this year, Shelby Miller was all the rage, and with good reason. Recently, of course, Michael Wacha has been the leader, winning NLCS MVP honors. And either of the duo out of the bullpen, Carlos Martinez and Trevor Rosenthal, starters both in the minor leagues, might end up being the best of the group.

All four are younger than Kelly. All four strike out more hitters, by far, than Kelly.

But Kelly pitched quite well into the sixth inning of the World Series' Game 3, helping the Cardinals to a vital 5-4 win. It's something he's been doing for some time now. And according to his manager, the Cardinals are aware of what Kelly has done for them this season.

"Maybe outside of this clubhouse, but I know, on this team, we realize how important it was that Joe stepped up when he did," Matheny said of Kelly prior to Saturday night's victory. "He became one of our top pitchers. We needed somebody to come in and start, fill a void for us, and Joe was as good as anybody in the league for a good stretch of time."

This isn't merely manager-speak on either count. Kelly made 15 starts for the Cardinals this season, 14 after July 1, and pitched to a 2.28 ERA in those starts. Just three starters, over a full season, put up a better raw ERA this year: Clayton Kershaw, Jose Fernandez and Matt Harvey.

Moreover, Kelly did so at a key time. With Jaime Garcia out for the season, Shelby Miller fading, and the Cardinals in need of five starters, that pitching surplus that has the world amazed wasn't anything like one over the grueling regular season. Rosenthal and especially Martinez have developed more since the middle of the season. Kelly, at the time, stepped in when needed.

What the Cardinals have to figure out now, though, is twofold: just how real was Kelly's low ERA this season? And how big a part of their future is he?

"He's got a great deal of confidence, and he should," Matheny said of Kelly. "Because he's got the stuff to back it up."

What's been fascinating, as it relates to Kelly, is that his stuff just hasn't translated to anything like the absurd strikeout numbers of many of his teammates. He throws a sinker around 60 percent of the time, and it sits at 96, frequently reaching 98-99, as it did Saturday night. He mixes in, in roughly equal doses, a slider at 85, a change around 83, and a curve at 79 miles per hour, along with the occasional four-seamer, also at 96.

This would seem to provide Kelly with the raw material to strike plenty of hitters out. But even in the minors, he never put up gaudy strikeout totals, and this season, while he's produced very effective results, he's struck out just 5.7 batters per nine innings. To put that in perspective, 81 starters qualified for the ERA title this year. 73 of them had a better strikeout rate than Joe Kelly.

As Bill James said in his New Historical Baseball Abstract, "The influence of strikeouts on a pitcher's future can be compared to the effect of height on a man's chances of playing in the NBA." And the Cardinals, unlike many other teams, have a whole bunch of very tall pitchers. So is Kelly going to need to change the way he pitches?

Not necessarily. David Schoenfield pointed out that Kelly succeeded this season without relying as much on the ground ball as, for instance, Derek Lowe at the height of his success. And Schoenfield is correct that if Kelly is ultimately to go the Lowe route, he'll need to increase his ground ball rate.

But all that means is that Kelly has more than one way to find permanent success. He can become a more extreme ground ball pitcher. Or if he can use his secondary pitches more effectively, he could start striking out more hitters, too. As Matheny said, he certainly has the stuff to do so.

That's certainly what happened on Saturday night. In his 5 1/3 innings, Kelly struck out six. He worked mostly in the bottom of the strike zone, but managed to get swings and misses with not only his sinker, but the changeup, the slider and the curve as well.

When it was over, Kelly insisted he wasn't doing anything different to get more of those necessary strikeouts.

"I was just attacking the zone with some fastballs, just trying to go after these guys," Kelly said, reflecting on his start from the World Series postgame podium, a trucker hat on backwards as he talked. "Keep my pitch count down, mixing offspeed pitches over the plate for a strike. I wasn't trying to do too much, trying to get too pumped up, too hyped up. But, I mean, I was just trying to throw strikes at that point, and it seemed to be working."

It's been working for a while now. But whether it can continue, when his ERA is so much lower than, for instance, his xFIP, is anything but certain. What makes Joe Kelly interesting, though, is that even though his stats scream regression, there's plenty within his raw stuff that argues for potential growth. And he may not be little more than a year out of college, like Wacha, but he's still just 25. That's old in Cardinals years, but not in normal pitcher years.

As Matheny put it, tying a question about Lance Lynn back to both Lynn and Kelly, "But I believe he's still a young pitcher, and still learning, and still adapting, a lot like how we talk about a Joe Kelly. I believe, earlier this season, Joe and Lance were both kind of [figuring out], what kind of pitcher am I? And that sounds kind of odd for a guy that's in the big leagues, but once they got here... am I gonna be a power pitcher, am I gonna pitch to contact, be a little more about movement?

"So these are things that they're both actually still sorting through. Both of them have the ability to throw with high velocity. So I think a lot of it's kind of a day-to-day adjustment, but kind of also getting philosophies together."

On Saturday night, anyhow, both came together for Kelly.

"He has the stuff to do that at times, but we like how he works ahead in the count, in the bottom of the zone, and gets ground balls," Matheny said of Kelly's performance when it was over. "That was working for him today, also. Joe did a good job, he had good stuff. He did a nice job today. And that's what we've seen, the last two months of the season, he's been very good, very consistent for us."